Oecomys catherinae is an arboreal rodent. Specimens from Brazil’s Atlantic Forest and Cerrado showed differences in skull form between the two biomes.
Skull form differed between specimens from the Atlantic Forest and Cerrado, with greater bony-palate length in the Atlantic Forest sample.
It uses trees in its daily life.
The dorsal fur is thick and sleek, ranging from brownish-orange to tawny chestnut.
Most of the tail is dusky brown all around, with a paler underside near the base. Tail hairs are short and do not form a distinct tuft.
An extinction-risk assessment has not been added yet.